1. Field of the Invention
The present invention relates to a gear-shifting mechanism driving device.
2. Description of Background Art
Heretofore, a gear-shifting mechanism for a driving device is known. See, for example, Japanese Patent Application Publication No. 2011-208766. This gear-shifting mechanism driving device includes a transmission (M) for selectively establishing a gear combination by the turning of a shift spindle (131) for turning a master arm (132), and an actuator (119) as a power source for turning the shift spindle (131).
In a structure (hereinafter referred to as a conventional example), as disclosed in Japanese Patent Application Publication No. 2011-208766, an inputting mechanism including the actuator (119) and a speed reduction mechanism (123) for a rotational driving force thereof and shift position change driving means (110) as an operating mechanism are separately disposed respectively on left and right sides of a crankcase, which also serves as a transmission case. Moreover, the operating mechanism includes the master arm (132) turning integrally with the shift spindle (131), and a stopper member restricting the amount of turning of the master arm (132) by the master arm (132) coming in contact with the stopper member. Further, the shift spindle (131) laterally passing through an inside of the crankcase is connected to the inputting mechanism and the operating mechanism, and a rotational driving force of the inputting mechanism is transmitted to the operating mechanism through the shift spindle (131).
In the gear-shifting mechanism driving device, in the case where gear-shifting speed is desired to be increased, the master arm (132) is turned at a high rotational speed. At this time, the master arm (132) comes in contact with the stopper member to be stopped. Accordingly, as the turning speed of the master arm (132) increases, an impact of the master arm (132) coming in contact with the stopper member increases. The impact is transmitted to the inputting mechanism through the shift spindle (131).
In the conventional example, to reduce the transmission of the impact, the transmission of the impact to the inputting mechanism is reduced by increasing the shaft length of the shift spindle (131) and making the shift spindle (131) easy to twist.
There are cases where a shift spindle has to be short, depending on the layout of the internal structure of an internal combustion engine or the like.
In this case, since the shaft length of the shift spindle becomes short, the shift spindle becomes difficult to twist. Accordingly, when the turning speed of the master arm is high, it is difficult for the shift spindle to sufficiently absorb an impact acting on the master arm when the master arm comes in contact with the stopper member. When the impact is transmitted to the inputting mechanism through the shift spindle, there is a possibility that the accuracy of the inputting mechanism is influenced. To improve the strength of the inputting mechanism to avoid the influence, the thicknesses and diameters of gears need to be increased, and there arises such a problem that the size of the inputting mechanism is increased.